The proposed study is intended to extend our earlier findings that small intestinal brush border-membrane disaccharidases play an additional role in the translocation into the cell of the products of hydrolysis. This has been termed Hydrolase-Related Transport (HRT). The mechanism(s) underlying HRT have not been clarified and these will be investigated using everted small intestinal segments in vitro and with isolated membrane vesicles that exhibit transport properties. The brush border oligopeptidases will be similarly studied for the role they play in digestion and absorption of peptides. Brush border guanylate cyclase will be investigated for the role it may play in controlling digestion and absorption by the small intestine. The results are expected to clarify at least some aspects of intestinal function and its control.